Sanding down hardwood flooring is a difficult job that, when done by an inexperienced do-it-yourselfer, has potential for disaster. A poor job can result in permanently wavy bumps or visible scratches. Our general advice is to hire a professional floor refinisher unless you’re accomplished at this type of home improvement.

Unless you’re doing a couple of small repairs or working in a tiny area, you’re going to need professional sanding equipment. Three main types of floor sanders are available; to do a complete job, you’ll need all three. To buy these, you would pay thousands of dollars; fortunately, you can rent them from a tool rental supply or major home improvement center such as Home Depot or Lowe’s.

You will also need a heavy-duty vacuum for keeping the dust down—most of these sanders are designed to be connected to dust-control vacuums. Talk with the rental desk about a vacuum that can be connected to the sanders.

Also buy enough sandpaper for your job. The amount and grits you will need depend upon the size of the floors and the nature of the finishes you’ll be removing. (Ask the dealer for recommendations.) When using any floor sander, you will be working from rough sandpaper that removes a lot of material (20-grit) to progressively less-abrasive sandpaper: 60-, 80-, and 120-grit to eliminate scratches and produce a fine finish.

Other supplies you’ll need include masking tape and plastic sheeting for protecting areas from sawdust. You can buy or rent the necessary safety equipment: a respirator, hearing protection, goggles, and work gloves.

Drum Sanders
A drum sander is used for the first stage of a floor-sanding job. You stand to operate this very heavy upright machine. It rolls an 8- or 12-inch-wide sandpaper belt across a series of drum rollers so that the sandpaper moves in a straight line. On unsanded new wood flooring, a drum sander may be operated on a diagonal to the wood grain at first to flatten the irregular surface. But for refinishing and finer sanding, it should be operated only in-line with the direction of the wood grain to avoid leaving scratches, skips, or chatter marks. To rent a drum sander, expect to pay from $50 to $75 a day.

Random-Orbital Sanders
A random-orbital sander is used to remove scratch patterns created by drum or rotary sanders, in preparation for the final finish. In addition, it is used in small areas and tight spaces where a drum sander would be difficult to maneuver, and on herringbone, parquet, and ornamental floors. This type is also used with fine-grit sandpaper for “screen and recoat” jobs, where minimal sanding is required.

At the orbital sander’s base, sandpaper is fitted to a flat pad that moves in minute back-and-forth and oval vibrating motions. Because of these tiny movements, this type of sander is much less prone to scratch the wood than sanders that move the sandpaper in one direction.

You can get types with a rounded base or a rectangular base. Floor models can be rented for about $30 to $50 per day. For very small work, you can buy palm-sized models for from $50 to $100.

Edge Sanders
An edge sander or “edger” is a smaller sander that you typically operate from a kneeling position. The edger is designed to work right up to base moldings and walls and go into tight spots where a drum sander can’t go. It includes a dust bag and has an orbital motion, like the random-orbital sanders above. You can buy an orbital sander for around $200 or rent one for about $30 per day.